1. Field of the Invention
The present invention relates to a vane pump and more particularly to a vane pump having a pressure chamber for reducing pressure pulsations of pressurized fluid discharged from the pump.
2. Discussion of the Related Art
A conventional vane pump is provided with a pressure chamber formed in a pump housing in order to reduce pressure pulsations of pressurized fluid discharged from the pump. In such a pump, pressurized fluid discharged from exhaust ports is supplied to a fluid device such as a power steering apparatus through the pressure chamber. With this configuration, when pressurized fluid discharged from exhaust ports flows into the pressure chamber, the pressure of the fluid falls due to an increase of the cross section of the fluid passage, whereby the pressure pulsations of the pressurized fluid is decreased.
Thus, in a conventional vane pump having above-mentioned structure, it is necessary to enlarge the volume of the pressure chamber in order to reduce the pressure pulsations efficiently. However, there is a limit to any such increase since the vane pump is desired to be small and light. Furthermore, since a pair of pressurized fluids having the same pressure phase are discharged from a pair of exhaust ports simultaneously, the pressure pulsation of the pressurized fluid is sometimes enhanced in the pressure chamber.